At March 31, 2020, we carried a total debt balance (including accrued interest) of €5,738.7 million, of which €1,511.5 million principal amount is related to the € and USD-denominated Senior Secured Fixed Rate Notes due March 2028 and €3,201.9 million principal amount is owed under our 2018 Amended Senior Credit Facility with maturities ranging from April 2028 through April 2029. Our total debt balance at March 31, 2020 also included a principal amount of €328.6 million related to our vendor financing program and €4.0 million for the outstanding portion of the 2G and 3G mobile spectrum licenses. The remainder primarily represents lease obligations associated with the Interkabel Acquisition and lease liabilities following the adoption of IFRS 16 as of January 1, 2019.
At March 31, 2020, we carried €328.6 million of short-term debt related to our vendor financing program, all of which is maturing within less than twelve months. This represented a decrease of €26.3 million versus December 31, 2019. For the full year 2020, we still anticipate our vendor financing program to remain relatively stable compared to the end of 2019. As of February 2020, we have reduced the applicable margin on our future short-dated commitments under the vendor financing program by 15 basis points to 2.10% over EURIBOR floored at 0%. Given the aforementioned size of the program, this will have a modest accretive impact on our Adjusted Free Cash Flow.
In January 2020, we successfully issued and priced a new 8.25-year USD 2,295 million Term Loan (“Facility AR”) and a new 9.25-year €1,110 million Term Loan (“Facility AQ”). We have used the net proceeds of these issuances to redeem in full the previous Term Loans AN and AO of USD 2,295 million and €1,110 million, respectively. Through this leverage-neutral transaction, we succeeded in reducing the margin on both term loans by 25 basis points, which further solidifies our Adjusted Free Cash Flow profile after the October 2019 refinancing of the 4.875% Senior Secured Notes due 2027.
In April 2020, we successfully issued a new 6.2-year €510.0 million revolving credit facility, replacing our current €460.0 million revolving credit facilities with certain availabilities up to June 2023. As such, we succeeded in extending and upsizing our revolving credit facilities, further strengthening our liquidity profile.
In April 2020, we also completed the 10% repurchase of our 3.50% €600.0 million Senior Secured Fixed Rate Notes due March 2028. As a result of this transaction, the principal amount under these Notes decreased to €540.0 million, leading to annual cash interest savings of €2.1 million further adding to our robust Adjusted Free Cash Flow profile.
Excluding short-term liabilities related to our vendor financing program, we face no debt maturities prior to March 2028 with an improved weighted average maturity of 8.3 years at March 31, 2020 following the aforementioned January 2020 refinancing of our term loan facilities. In addition, we also had full access to €505.0 million of undrawn commitments under our revolving credit facilities at March 31, 2020 with certain availabilities up to June 2023. On a pro forma basis - to reflect the issuance of the new RCF as mentioned above - our undrawn commitments would have totaled €555.0 million at March 31, 2020 with certain availabilities up to May 2026.
For more information on our debt instruments and payment schedule at March 31, 2020, we refer to the Q1 2020 Investor & Analyst Toolkit.